In connection with transport, weighing, processing, handling etc. of a wide variety of items, including food products such as pieces of meat, e.g. pieces of meat from fish, poultry, cattle etc. or other food products, it is desired to be able to pick-up or grip such items and move or transfer such items one by one. This is in particular the case when such items are feed in an unorderly form, possibly with a plurality of items piled up, in which case it will be difficult to grip the individual items. Furthermore, it is desirable to be able to pick-up or grip such items and move or transfer such items one by one when it is of importance that the items are delivered and transported further on with a predefined minimum mutual distance, for example required in view of a subsequent processing or handling of the items.
It is known to use various vacuum transport devices in such connections.
Such devices have been disclosed for example in EP 619249 A1, EP 1021361 B, NL 9102028 and WO 2005/035405 A1.
In EP 619249 A1 and EP 1021361 B devices are disclosed which use gripping elements which are placed in a circular configuration in such a manner that the gripping elements are moved in an essentially horizontal plane. The suction effect is achieved by means of a vacuum source, which may be connected to the individual gripping elements in a controllable manner. The gripping elements are controlled to pick-up individual items at a first position and deliver the items at a second position along the circular path.
In NL 9102028 a device for picking up fish is disclosed, which device comprises a wheel placed with its axis of rotation horizontally and with a plurality of suction cups placed at the perimeter of the wheel and facing radially outwards. The wheel has to be moved at least partially through the container, from which the fish are picked.
WO 2005/035405 A1 discloses a rotating cylinder which is placed with its axis of rotation horizontally and which has a number of suction openings at its cylindrical surface. Vacuum from a vacuum source is connected to the suction openings via tubes in the cylinder body and a manifold arrangement placed at one end of the rotating cylinder.
The above-mentioned prior art devices are provided with various mechanical devices in order to control the suction effect, e.g. in order to achieve that the vacuum is disconnected at the location, where it is desired to deliver the items. Such mechanical devices may add to the complexity of the device and may hinder an effective cleaning of the device. Furthermore, it is noted that these devices all have a static configuration in as the transport path is restricted by the circular arrangements and in as the locations, where the items can be picked-up and delivered, are given by the configuration of the structures, meaning that these prior art devices lack flexibility in this regard.
Furthermore, it is known to use a conveyor belt having suction openings for transporting items, where vacuum is connected to the suction openings. Such vacuum conveyor belt arrangements for transporting items are also disclosed in the prior art in various forms, as it will be explained in the following.
In U.S. 2005/0072654 A1, for example, a conveyor assembly for separating and transporting articles is described, which assembly comprises a vacuum conveyor in the form of a non-rotating vacuum drum and an endless belt which moves about the periphery of the drum. The belt is provided with an arrangement of openings along the length of the belt at preselected positions in order to allow for vacuum engagement of the articles. The belt is driven about the vacuum drum in such a manner that the belt is in contact with the drum for approximately half the periphery of the drum and articles which are engaged by an opening of the belt in this area can be transported by the belt along the periphery of the drum. The manner in which vacuum is led to the openings in the belt is not described, however, but it is indicated that at the location where the belt leaves the periphery of the drum, the suction effect of the openings is disrupted and the articles are released. The articles may be engaged at the top of the drum and transported down to the bottom of the drum or vice versa. In both cases articles, which are not engaged by a suction hole or which are not properly engaged, will fall down into a chute and will be fed back to a feed conveyor. Also, in both cases it is necessary to have a feeding conveyor as well as a pick-up conveyor for handling the articles, that are transported by the device.
EP 0 827 918 A2 discloses a conveyor belt comprising an endless belt being driven in a path having an upper and a lower run, which are horizontal. The belt comprises vacuum recesses which are connected to vacuum channels emerging on the rear of the belt. Above the lower run of the belt a number of vacuum boxes are placed end to end, which vacuum boxes are connected to a vacuum source. Thus, items fed to the lower side of the conveyor at one end can be transported to the other end hanging below the conveyor belt, i.e. a distance corresponding at most to the total length of the vacuum boxes and only in a horizontal direction.
In JP 2070616 A vacuum conveyor belts are applied for removing lids from boxes, where two vacuum conveyor belts are arranged essentially in parallel, but displaced in the longitudinal direction. The boxes are transported by means of a first vacuum conveyor towards a second vacuum conveyor, and when a box has reached a location between these two conveyors, the first vacuum conveyor belt is lifted upwards, whereby the lid of the box engages the lower run of the second vacuum conveyor belt and is gripped by a suction hole in the lower run of the second vacuum conveyor belt. Further, the main body of the box is withheld to the first vacuum conveyor belt by means of the action of a vacuum box placed under the first conveyor belt. As the two conveyors move away from each other, the lid is removed from the box and carried further by the second vacuum conveyor belt. The vacuum arrangement of the second vacuum conveyor belt comprises an elongated vacuum box placed above the lower run of the belt, whereby two rows of holes in the belt may be subjected to vacuum when passing the vacuum box.
Further, U.S. Pat. No. 3,722,665 A describes a vacuum elevating conveyor, where articles are elevated using a conveyor with an endless belt that is arranged with a steep inclination and with an elongated vacuum box beneath the upper run of the belt. The belt comprises vacuum holes, whereby articles may be engaged at the lower end of the conveyor belt, withheld due to the suction and carried upwards on the belt for further transport, when released from the belt at the end of the vacuum box.
As it will be understood, also these prior art devices all have static configurations in as the transport path is restricted and in as the locations, where the items can be picked-up and delivered, are given by the configuration, meaning that these prior art devices also lack flexibility in this regard.
Thus, it is an object of the invention to provide an improved vacuum transfer device.
In particular, it is an object of the invention to provide such a transfer device, which provides an improved flexibility, for example as regards applications, feeding and/or outlet options, etc.
Furthermore, it is an object of the invention to provide such a transfer device, which facilitates an effective and relatively easy cleaning of the device.
Still further, it is an object of the invention to provide such a transfer device, by means of which items that are not gripped or that are released during the transfer, do not require special facilities or operations for being offered for transfer again.
These and other objects are achieved by the invention as it will be explained in detail in the following.